We report a diffractive-lens triplet with which to achieve wavelength compensation in the near field diffracted by any aperture. On the one hand, the all-diffractive triplet allows us to tune, in a sequential way, the Fresnel-irradiance shape to be achromatized by changing the focal length of one diffractive lens. On the other hand, we can adjust the scale of the chromatically compensated Fresnel diffraction field by shifting the aperture along the optical axis. Within this framework, we present an extremely flexible white-light Fresnel-plane array illuminator based on the kinoform sampling filter. A variable compression ratio and continuous selection of the output pitch are the most appealing features of this novel application.
© 2005 Optical Society of America
(050.1970) Diffraction and gratings : Diffractive optics
(070.2580) Fourier optics and signal processing : Paraxial wave optics
(070.2590) Fourier optics and signal processing : ABCD transforms
(070.6760) Fourier optics and signal processing : Talbot and self-imaging effects
Fourier Optics and Signal Processing
G. Mínguez-Vega, M. Fernández-Alonso, E. Tajahuerce, J. Lancis, Z. Jaroszewicz, and P. Andrés, "Chromatic compensation in the near-field region: shape and size tunability," Appl. Opt. 44, 6933-6939 (2005)